Microporous crystalline aluminophosphate compositions having open framework structures formed of AlO.sub.2 and PO.sub.2 tetrahedral units joined by the sharing of the corner oxygen atoms and characterized by having pore openings of uniform dimensions have heretofore been disclosed in a number of publications, notably the specification of U.S. Pat. No. 4,310,440 issued July 7, 1980 to S. T. Wilson et al. The Wilson et al. aluminophosphates constitute a generic class of non-zeolite molecular sieve materials which are capable of undergoing complete and reversible dehydration while retaining the same essential framework topology in both the anhydrous and hydrated state. By the term "essential framework topology" or "essential framework structure" as used in the aforesaid patent, and also in the present specification and claims, is meant the spatial arrangement of the primary Al--O and P--O bond linkages. Other microporous aluminophosphates which undergo structure rearrangements, either reversibly or irreversibly, upon partial or complete dehydration are also known, for example the minerals variscite and metavariscite and certain of the synthetic metastable aluminophosphates reported by F. D'Yvoire [Bull. Soc. Chim. France, 1762 (1961)]. Another class of synthetic crystalline compositions which contain framework tetrahedral metal oxides of manganese, magnesium, cobalt and/or zinc in addition to the AlO.sub.2 and PO.sub.2 tetrahedra are disclosed in commonly assigned U.S. Pat. No. 4,567,029, issued on Jan. 28, 1986 (MeAPO). Yet, another class of synthetic crystalline compositions which contain framework tetrahedral silicon dioxide in addition to the AlO.sub.2 and PO.sub.2 tetrahedra is disclosed in commonly assigned U.S. Pat. No. 4,440,871, issued on Apr. 3, 1984 (SAPO).